The expression “battery of accumulators” is used to mean the series connection of a number of accumulators or of accumulators in parallel.
The charging of an accumulator is reflected in an increase in the voltage at its terminals. An accumulator is considered to be charged when it has reached a voltage level defined by the electrochemical process.
Furthermore, the lithium-ion technology batteries have a minimum threshold voltage below which the accumulators of the battery may be damaged or destroyed, which can result in malfunctioning of the battery, for example the current is blocked and the battery no longer delivers any energy.
Furthermore, in a circuit using a number of accumulators connected in series, it is highly probable that the level of charge of each accumulator is not the same. This is because it is possible for one accumulator to be discharged before the other accumulators of the battery.
Consequently, it is essential to stop the discharging of the battery when the voltage of the least charged accumulator falls below the minimum threshold voltage, even if there is still energy in the other accumulators to avoid a malfunctioning of the battery and damage to the least charged accumulator.
It is then essential to monitor in detail the voltage of each accumulator during discharge to check that no accumulator reaches the minimum threshold voltage.